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		<title>Document</title>
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		<script>
			// 原型对象的应用   扩展内置对象方法
			console.log(Array.prototype);

			Array.prototype = function () {
				let sum = 0;
				for (let i = 0; i < this.length; i++) {
					sum += this[i];
				}
				return sum;
			};

			// 注意：数组和字符串内置对象不能给原型对象覆盖操作 Array.prototype = {}; ，只能是 Array.prototype.xxx = function () {};

			console.log(Array.prototype);

			let arr = [1, 2, 3];
			console.log(arr.sum());

			let arr0 = new Array(11, 22, 33);
			console.log(arr0.sum());
		</script>
	</body>
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